SIMBAD references

2025A&A...699L..11V - Astronomy and Astrophysics, volume 699L11 (2025/7-1)

The CHIMERA Survey: The first CO detection in Leo T, the lowest mass known galaxy still hosting cold molecular gas.

VILLANUEVA V., BLANA M., BOLATTO A.D., RUBIO M., TARANTINO E., HERRERA-CAMUS R., BURKERT A., VAZ D., READ J.I., GALAZ G., MUNOZ C., CALDERON D., BEHRENDT M., CARBALLO-BELLO J.A., GRAY E. and FELLHAUER M.

Abstract (from CDS):

We report the first CO detection in Leo T, representing the most extreme observation of carbon monoxide molecules in the lowest stellar mass gas-rich dwarf galaxy (M⋆ ∼ 105 M⊙) known to date. We acquired and present new Atacama Compact Array (ACA) 12CO(J = 1-0) data within our CHIMERA Survey project for the central region of Leo T, a metal-poor ([M/H] ∼ -1.7) dwarf in the Milky Way (MW) outskirts. We identified three compact molecular clouds (< 13 pc) with estimated upper limit virial masses of Mmol ∼ 5 × 103 M⊙ each and a total of 1.4 ± 0.4 × 104 M⊙, corresponding to ∼3% of the total gas mass. We obtained CO-to-H2 conversion factors (αCO) as high as ∼ 155 M⊙(K km s–1 pc2)–1 and mean molecular gas surface densities of Σmol ∼ 9 M⊙ pc–2 that are consistent with values found in dwarf galaxies with extremely low metal content. All CO clouds are shifted (∼60 pc) from the stellar population centers, and only one cloud appears within the densest HI region. Two clouds have velocity offsets with the HI of Δvlos ∼ + 13 km s–1 being within twice the velocity dispersion (Δvlos/σ_HI, los_ ∼ 2) and probably bound. However, the northern cloud is faster (Δvlos ∼ + 57 km s–1); our models with low halo masses (Mh ≲ 109 M⊙) result in unbound orbits, suggesting that this material is likely being expelled from the dwarf, providing evidence for molecular gas depletion. These properties reveal a perturbed dynamics intertwined with star formation processes in low-mass dwarf galaxies, supporting a scenario of episodic bursts until they are fully quenched by the MW environment.

Abstract Copyright: © The Authors 2025

Journal keyword(s): galaxies: dwarf - galaxies: evolution - galaxies: ISM - Local Group

Simbad objects: 11

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